As part of the German site selection procedure for deep geological disposal of high-level radioactive waste (HLW), an investigation, according to federal regulations, must be undertaken into whether potential sites for HLW are also suitable for the additional disposal of low- and intermediate-level radioactive waste (L/ILW) at the same site in a separate repository area. In order to assess this option, the mutual influences that could emanate from the two different repository areas need to be examined.

To this end the GemEnd research project has investigated the identification and assessment of processes that could arise from a repository at the same site for both HLW and L/ILW. The research project was carried out on behalf of the Federal Office for the Safety of Nuclear Waste Management (BASE).

The present paper provides a brief overview of international concepts for a combined repository and their findings on potential safety-relevant processes and the resulting minimum safety distances between the repository areas in the respective host rock. These potentially safety-relevant thermal, hydraulic, mechanical, chemical, and biological processes are compared with the results of the GemEnd research project for the three host rock types permitted in Germany, namely, rock salt, clay rock, and crystalline rock.

Finally, similarities and differences in the joint disposal concepts and the international investigations into the extent of the identified processes are analyzed in order to assess the transferability of the obtained findings to the site selection procedure in Germany.